Abstract

Measurements of the spectrum of Fe24+ in the 1.845 Å to 1.885 Å range obtained on the EBIT‐I electron beam
ion trap at Lawrence Livermore National Laboratory were used for determining the radiative lifetime of the 1s2p 1P1
excited state. The spectrum contains electric dipole forbidden transitions at 1.855Å (“x”) and 1.868Å (“z”) whose lineshape is well represented by a Gaussian line profile and is assumed to be due primarily to Doppler and instrumental broadening. The Gaussian contribution is assumed to be the same for all lines in the spectrum. This assumption simplifies the problem when considering a more complex combination of broadening mechanisms. For allowed transitions such as 1s2p1P1 → 1s21S0, “w”, at 1.850 Å we assume a Voigt profile. In the simplest case this combines both natural (Lorentzian) and Doppler (Gaussian) broadening effects which contribute to the width of the spectral line. With the Gaussian contribution determined from lines “x” and “z”, deconvolving the Gaussian from the Voigt profile gives the natural line width. This then is directly related to the radiative lifetime of the 1s2p 1P1 excited level.